OCCURRENCE OF A GROWTH INHIBITOR, 3-HYDROXY-BETA-IONONE, IN 7 CULTIVARS OF PHASEOLUS-VULGARIS AND ITS ROLE IN LIGHT-INDUCED GROWTH-INHIBITION

The amounts of the growth inhibitor 3-hydroxy-beta-ionone were measured in extracts of the hypocotyls of seven cultivars of dark-grown bean seedlings (Phaseolus vulgaris) 24 hr after the onset of light irradiation, and compared with measurements of light-induced growth inhibition. The concentration of the inhibitor in the hypocotyls of these cultivars increased 2.5-4 x in response to light, and the changes in its levels in the hypocotyls of each cultivar were closely correlated with the light-induced inhibition of growth of the hypocotyls of the respective cultivars. The present results suggest that the endogenous growth inhibitor, 3-hydroxy-beta-ionone, may play an important role in the inhibition by light of hypocotyl growth of these cultivars and so may affect the growth habit of these cultivars.